The present invention relates to a method for the preparation of anisalcohol (methoxybenzyl alcohol) by hydrogenation of anisaldehyde (methoxybenzaldehyde) in the presence of Raney nickel and a basic additive, the use of the anisalcohol and hygiene or care products containing anisalcohol.

1. A method for the preparation of anisalcohol by hydrogenation of anisaldehyde, wherein said hydrogenation is carried out in the presence of Raney nickel and a basic additive comprising a metal hydroxide or metal alcoholate.

2. A method according to claim 1, characterised in that the basic additive comprises sodium hydroxide, potassium hydroxide, sodium methylate or sodium ethylate.

3. Fragrance mixtures, perfume compositions, perfume oils or scent compositions containing anisalcohol which has been prepared according to claim 1.

4. Hygiene or care products containing anisalcohol which has been prepared according to claim 1.

Description:

The present invention relates to a method for the preparation of anisalcohol (methoxybenzyl alcohol) by hydrogenation of anisaldehyde (methoxybenzaldehyde) in the presence of Raney nickel and a basic additive, the use of the anisalcohol and agents containing anisalcohol.

The hydrogenation of anisaldehyde to anisalcohol using Raney nickel with the addition of platinum(IV) chloride and triethylamine is described in J. Am. Chem. Soc. 1959, 72, 1190. The hydrogenation is carried out in ethanol as solvent and gives anisalcohol in 86% yield.

The electrocatalytic hydrogenation of anisaldehyde to anisalcohol using Raney nickel is described in Bull. Chem. Soc. Jp. EN 3, 1983, 56, 719. The nickel cathode is coated with Raney nickel powder and in methanolic solution at room temperature leads to anisalcohol in 71% yield.

The known methods are, on the one hand, not satisfactory because of the expensive catalysts, some of which are also laborious to prepare; on the other hand, the yields are inadequate.

The aim was to find a method for the preparation of anisalcohol that is able to yield the anisalcohol in better yield and in high purity.

The present invention therefore relates to a method for the preparation of anisalcohol by hydrogenation of anisaldehyde, characterised in that the hydrogenation is carried out in the presence of Raney nickel and a basic additive selected from the series comprising metal hydroxides or metal alcoholates.

A further subject of the present invention is the use of the anisalcohol prepared according to the invention as a fragrance and also agents containing this anisalcohol.

The method according to the invention enables, in particular, the preparation of anisalcohol that is flawless from the sensory standpoint, in particular under economic aspects and on the industrial scale.

The hydrogenation of epoxides in the presence of Raney nickel and a basic substance is described in WO-A 2000/26165.

o-Anisaldehyde, p-anisaldehyde, m-anisaldehyde or an arbitrary mixture of the said aldehydes can be used for the method according to the invention. p-Anisaldehyde is preferably employed in the hydrogenation.

For the method according to the invention the Raney nickel can be used in the dry or moist state (water content up to 70% (m/m)).

For the method according to the invention the weight ratio of the Raney nickel employed to anisaldehyde is 0.0001 to 0.1 to 1, preferably 0.001 to 0.05 to 1, particularly preferentially 0.01 to 0.02 to 1.

For the method according to the invention the basic additive can be a metal hydroxide or a metal alcoholate. Alkali metal hydroxides and alkaline earth metal hydroxides and also alkali metal alcoholates and alkaline earth metal alcoholates are preferred, the alcoholates preferably having no more than 4 carbon atoms. Particularly preferred basic additives are sodium hydroxide, potassium hydroxide, sodium methylate and sodium ethylate.

The basic additives can be employed in the pure form or in the form of solutions. Aqueous solutions are particularly suitable in the case of the hydroxides and alcoholic solutions are particularly suitable in the case of the alcoholates.

For the method according to the invention the weight ratio of the basic additive employed, based on the pure form thereof, to anisaldehyde is 0.000001 to 0.1 to 1, preferably 0.00001 to 0.01 to 1, particularly preferentially 0.0001 to 0.001 to 1.

According to the invention the method is carried out at 30-180° C., preferably at 70-130° C., and particularly preferentially at 80-100° C.

The method according to the invention is carried out with hydrogen; the hydrogen pressures are usually in the range of 1 to 100 bar abs.; it is preferred to carry out the reaction under hydrogen pressures in the range of 5 to 50 bar abs., in particular in the range of 10 to 20 bar abs.

The reaction time is usually in the range of 2 to 100 hours, preferably in the range of 5 to 40 hours and particularly preferentially in the range of 20 to 25 hours.

The method can be carried out continuously, semi-continuously and discontinuously.

The method according to the invention can, for example, be carried out as follows:

Anisaldehyde, Raney nickel and basic additive are initially introduced into a pressure vessel. The hydrogenation is carried out at the selected temperature and under the selected hydrogen pressure. After the end of the hydrogenation, the crude anisalcohol can be obtained by removal of the Raney nickel (for example by filtration, decanting or centrifuging) and, if appropriate, by removal of the basic additive via washing operations. If required, a further purification of the anisalcohol can be carried out, for example by distillation.

According to the method according to the invention, anisalcohol can be obtained in a purity of more than 99% and a distilled yield of 99%.

The anisalcohol prepared by the method according to the invention can be used without further purification steps; in particular, it is of good quality from the perfume standpoint.

The anisalcohol prepared by the method according to the invention can be used in particular as a fragrance, in fragrance mixtures, perfume compositions, perfume oils or scent compositions.

Hygiene or care products, in particular in the field of household products and personal hygiene products, are a further field of use.

EXAMPLE

3000 g anisaldehyde (GC purity 99.7%.), 7.5 g 21% sodium methylate solution in methanol and 57 g moist Raney nickel (50% water content) were initially introduced into a stirred autoclave with gasifying stirrer. The hydrogenation was carried out for 21 hours at 80 to 100° C. and 13 bar. After filtration, 3015 g anisalcohol with a purity of 99.1% were obtained. It was possible to distil the anisalcohol obtained at 130° C. sump temperature and 1 m bar vacuum. The yield of theory was 99% (sic).